Tens of thousands of people marched through London in protest against Britain's refugee policy, with new Labour Party leader Jeremy Corbyn attending in his first political engagement only hours after being elected.

Hong Kong police arrested more than 500 protesters at a sit-in early Wednesday following a huge pro-democracy rally that organisers said mobilised half a million people demanding the right to choose their next leader.

Dozens of protesters clashed with police late Friday, throwing fireworks and torching at least two vehicles near Sao Paulo's airport, which has just opened a new international terminal ahead of the World Cup.

Taiwan police on Monday used water cannon to dislodge hundreds of overnight sit-in demonstrators, demanding the scrapping of a nearly completed nuclear power plant, one of the most controversial issues to have gripped the island for 30 years.